chore: add toolkit-lib to the set of locally tested packages (#463)

Without these changes we only ever test against the publicly released
version of `@aws-cdk/toolkit-lib`.

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under the terms of the Apache-2.0 license

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Co-authored-by: github-actions <github-actions@github.com>

Author: rix0rrr

.github/workflows/integ.yml

@@ -812,6 +812,7 @@ const toolkitLib = configureProject(
         module: 'NodeNext',
       },
     },
+    nextVersionCommand: 'tsx ../../projenrc/next-version.ts maybeRc',
   }),
 );
 
@@ -1669,6 +1670,7 @@ new CdkCliIntegTestsWorkflow(repo, {
     cliLib.name,
     cdkAliasPackage.name,
     cliInteg.name,
+    toolkitLib.name,
   ],
 
   allowUpstreamVersions: [